The present invention relates to burners and, in particular, to a burner which is substantially self-regulating where the amount of fuel burned depends substantially on the size of the orifice through which the fuel vapors are exhausted.
Apparatus for preheating fuels in order to achieve more efficient burning are well known. For example, in U.S. Pat. No. 1,134,667, the fuel for an internal combustion engine is preheated by passing the fuel line through the entire length of an exhaust manifold. As another example, in U.S. Pat. No. 675,076, a hydrocarbon burner is disclosed in which a small orifice is placed in one part of a coil in a fuel line. Fuel escaping through the orifice is ignited causing the coil and, thus, the fuel therein, to be heated. The heated fuel is finally exhausted through the end of the coil where the primary burning occurs. A similar type of apparatus was also disclosed in U.S. Pat. No. 1,230,735, where a device is provided for preheating a kerosene fuel line to vaporize the kerosene and thus facilitate burning.
In each of the above patents, however, the primary and essential function is to preheat the fuel to facilitate burning as the fuel is exhausted from a second remote orifice at the end of the fuel line. By contrast, the present invention, while providing a preheating function to facilitate vaporization, also provides a backpressure portion which is also heated for providing a self-regulating capability.
More particularly, the present invention comprises a preheating pipe portion and an enclosed backpressure portion, both of which are heated in the primary burner flame. Connecting the preheater portion and the backpressure portion is an orifice pipe portion having an orifice through which the fuel is exhausted to be burned. It should be noted that, unlike the prior devices, the present invention has only a single orifice means with heat preheating being done in the primary flame. Thus, there is no separate secondary or preheating flame required as is the case with U.S. Pat. Nos. 1,230,735 and 675,076.
Because the backpressure generated by the present system is believed to simultaneously impede vaporization and promote exhaustion from the orifice, an equilibrium point is achieved at which the backpressure, and the temperature, are believed to be substantially constant. Because the equilibrium point is stable, the backpressure which is proportional to the temperature of the flame, provides a self-regulating effect where the amount of fuel exhausted from the orifice is dependent upon the pressure which, in turn, is dependent upon the temperature of the flame. The values of various parameters to obtain the most efficient burning are believed to occur at the equilibrium condition. In other words, the pressure regulates the amount of fuel exhausted to achieve the highest temperature and, therefore, the highest pressure and consequently the most efficient burning.
The present invention not only provides greater economy by causing the most heat energy to be extracted from a given quantity of fuel, but also provides a burner which is virtually pollution free and which can use any fuel whether liquid or gas. Furthermore, the present invention does not require complex valves or burner jets.